Re: BGP Community - AS0 is de-facto "no-export-to" marker - Any ASN reserved to "export-only-to"?'

[Tom Beecher <beecher () beecher cc>]

I completely agree that there is value for people sharing different
community structures that they have created for certain use cases. Such
things are generally useful for both operators of any experience level.

On Fri, Sep 11, 2020 at 8:08 AM <adamv0025 () netconsultings com> wrote:

> Reg the BCP38 vs RFC I guess is point in case (standard or best practice,
> the adoption is still low)
>
>
>
> Reg the community tagging design,
>
> Well it’s daily job of architects/designers to come up with new designs,
> standards and frameworks that can then be adopted by engineering/ops or
> automation system workflows or the business as a whole.
>
> Now would it be useful to have a reference design for various L2VPN
> options, or RR infrastructures, hub-spoke RT allocations, community tagging
> designs, or BGP input sanity checking, if nothing else like food for
> thought, sure…
>
>
>
> adam
>
>
>
> *From:* Jeff Tantsura <jefftant.ietf () gmail com>
> *Sent:* Wednesday, September 9, 2020 6:01 PM
> *To:* adamv0025 () netconsultings com
> *Cc:* nanog () nanog org
> *Subject:* Re: BGP Community - AS0 is de-facto "no-export-to" marker -
> Any ASN reserved to "export-only-to"?'
>
>
>
> BCP38 is an RFC, 2827.
>
> It is a grand advise if you can:
>
> -find someone who is actually well versed
>
> -afford that someone.
>
>
>
> Personally - when in early 2000s I had to write complete community tagging
> design for a multi country network, I wish I had  a “how to”
>
> Regards,
>
> Jeff
>
>
>
> On Sep 9, 2020, at 15:35, adamv0025 () netconsultings com wrote:
>
> 
>
> My advice to “someone who is setting up a new ISP and has a very little
> clue as where to start” would be just don’t and instead hire someone who’s
> well versed in this topic.
>
> But I see what you mean, RFC7938 was a good food for thought. But at the
> same time I’m sceptical, for instance would it help if BCP38 was an RFC?
>
> Would be nice for instance if the community could put together a checklist
> of things to consider for ISPs (could be in no particular order) (and
> actually there are such lists albeit concentrated around security)
>
>
>
> adam
>
>
>
> *From:* Jeff Tantsura <jefftant.ietf () gmail com>
> *Sent:* Wednesday, September 9, 2020 9:52 AM
> *To:* adamv0025 () netconsultings com
> *Cc:* nanog () nanog org
> *Subject:* Re: BGP Community - AS0 is de-facto "no-export-to" marker -
> Any ASN reserved to "export-only-to"?'
>
>
>
> I don’t think, anyone has proposed to use ‘’reserved ASNs” as a BCP,
> example of “ab”use of ASN0 is a de-facto artifact (unfortunate one).
>
> My goal would be to provide a viable source of information to someone who
> is setting up a new ISP and has a very little clue as where to start. Do’s
> and don’t’s wrt inter-domain communities use.
>
>
>
> I really enjoyed the difference RFC7938 (Use of BGP for Routing in
> Large-Scale Data Centers) made, literally 100s of companies have used it
> to educate themselves/ implemented their DC networking.
>
>
>
> Cheers,
>
> Jeff
>
>
>
>
> On Sep 9, 2020, at 10:04, adam via NANOG <nanog () nanog org> wrote:
>
> 
>
> I don’t agree with the use of reserved ASNs, let alone making it BCP,
> cause it defeats the whole purpose of the community structure.
>
> Community is basically sending a message to an AS. If I want your specific
> AS to interpret the message I set it in format YOUR_ASN:<community value>,
> your AS in the first part of the community means that your rules of how to
> interpret the community value apply.
>
> Turning AS#0 or any other reserved AS# into a “broadcast-AS#” in terms of
> communities (or any other attribute for that matter) just doesn’t sit right
> with me (what’s next? multicast-ASNs that we can subscribe to?).
>
> All the examples in Robert’s draft or wide community RFC, all of them use
> an example AS# the community is addressed to (not some special reserved
> AS#).
>
>
>
> Also should something like this become standard it needs to be properly
> standardized and implemented as a well-known community by most vendors
> (like RFCs defining the wide communities or addition to standard
> communities like no_export/no_advertise/…). This would also eliminate the
> adoption friction from operators rightly claiming “my AS my rules”.
>
>
>
> adam
>
>
>
>
>
> *From:* NANOG <nanog-bounces+adamv0025=netconsultings.com () nanog org> *On
> Behalf Of *Douglas Fischer via NANOG
> *Sent:* Tuesday, September 8, 2020 4:56 PM
> *To:* NANOG <nanog () nanog org>
> *Subject:* BGP Community - AS0 is de-facto "no-export-to" marker - Any
> ASN reserved to "export-only-to"?'
>
>
>
> Most of us have already used some BGP community policy to no-export some
> routes to some where.
>
> On the majority of IXPs, and most of the Transit Providers, the very
> common community tell to route-servers and routers "Please do no-export
> these routes to that ASN" is:
>
>  -> 0:<TargetASN>
>
>
>
> So we could say that this is a de-facto standard.
>
>
>
>
>
> But the Policy equivalent to "Please, export these routes only to that
> ASN" is very varied on all the IXPs or Transit Providers.
>
>
>
>
>
> With that said, now comes some questions:
>
> 1 - Beyond being a de-facto standard, there is any RFC, Public Policy, or
> something like that, that would define 0:<TargetASN> as "no-export-to"
> standard?
>
>
>
> 2 - What about reserving some 16-bits ASN to use <ExpOnlyTo>:<TargetASN>
> as "export-only-to" standard?
>
> 2.1 - Is important to be 16 bits, because with (RT) extended communities,
> any ASN on the planet could be the target of that policy.
>
> 2.2 - Would be interesting some mnemonic number like 1000 / 10000 or so.
>
>
>
> --
>
> Douglas Fernando Fischer
> Engº de Controle e Automação